Hackaday Prize 2022: A Backup Battery Pack

These days, we’re all running around toting smartphones and laptops that could always use a bit more charge. Portable battery packs have become popular, and [Anuradha] has designed one that packs plenty of juice to keep everything humming.

The pack is designed to be charged via solar panels, at 18 V and up to 5 A of current. It’s intended to work with a Maximum Power Point Tracking module to ensure the maximum energy is gained from the sunshine available. For storage, the pack relies on 75 individual 18650 lithium cells, arranged with 3 cells in series, each with 25 in parallel (3s25p). They’re spot welded together for strength and good conductivity. Nominally, the output voltage is on the order of 10-12 V. The included battery management system (BMS) will allow an output current up to 100 A, and the pack can be used with an AC inverter to power regular home appliances.

Overall, it’s a tidy pack that’s more than capable of keeping a few devices charged up for days at a time. If you’re building something similar yourself, though, just be sure to package it well and keep it protected. So many lithium batteries can quickly turn fiery if something goes wrong, so store and use it appropriately! Fear not, however – we’ve got a guide on how to do just that.

Ryobi Battery Hack Keeps CPAP Running Quietly

When it comes to cordless power tools, color is an important brand selection criterion. There’s Milwaukee red, for the rich people, the black and yellow of DeWalt, and Makita has a sort of teal thing going on. But when you see that painful shade of fluorescent green, you know you’ve got one of the wide range of bargain tools and accessories that only Ryobi can offer.

Like many of us, Redditor [Grunthos503] had a few junked Ryobi tools lying about, and managed to cobble together this battery-powered inverter for light-duty applications. The build started with a broken Ryobi charger, whose main feature was a fairly large case once relieved of its defunct guts, plus an existing socket for 18-volt battery packs. Added to that was a small Ryobi inverter, which normally plugs into the Ryobi battery pack and converts the 18 VDC to 120 VAC. Sadly, though, the inverter fan is loud, and the battery socket is sketchy. But with a little case modding and a liberal amount of hot glue, the inverter found a new home inside the charger case, with a new, quieter fan and even an XT60 connector for non-brand batteries.

It’s a simple hack, but one that [Grunthos503] may really need someday, as it’s intended to run a CPAP machine in case of a power outage — hence the need for a fan that’s quiet enough to sleep with. And it’s a pretty good hack — we honestly had to look twice to see what was done here. Maybe it was just the green plastic dazzling us. Although maybe we’re too hard on Ryobi — after all, they are pretty hackable.

Thanks to [Risu no Kairu] for the tip on this one.

Fighting Back Against Dodgy Dyson Batteries

If you’ve ever worked with multi-cell rechargeable battery packs, you know that the individual cells will eventually become imbalanced. To keep the pack working optimally, each cell needs to be analyzed and charged individually — which is why RC style battery packs have a dedicated balance connector. So if you know it, and we know it, why doesn’t Dyson know it?

It’s that question which inspired [tinfever] to start work on the FU-Dyson-BMS project. As you might have surmised from the name, [tinfever] believes that Dyson has intentionally engineered their V6 and V7 batteries to fail by not using the cell balancing function of the onboard ISL94208 battery management IC. What’s worse, once the cells get as little as 300 mV out of balance, the controller considers the entire pack to be shot and will no longer allow it to be charged.

These missing resistors deserve justice.

Or at least, that’s what used to happen. With the replacement firmware [tinfever] has developed, the pack’s battery management system (BMS) will ignore imbalanced cells so you can continue to use the pack (albeit at a reduced capacity). Of course the ideal solution would have been to enable cell balancing on the ISL94208, but unfortunately Dyson didn’t include the necessary resistors on the PCB. Though it’s worth noting that earlier versions of the board did have unpopulated spots for them, lending some credence to the idea that their omission was intentional on Dyson’s part.

But not everyone is onboard with the conspiracy theory. Over on the EEVBlog forums, some users pointed out that a poorly implemented cell balancing routine can be more problematic than not having one at all. It’s possible that Dyson had some bad experiences with the technology in earlier packs, and decided to move away from it and try to compensate by using higher-quality cells. That said, at least one person in the thread was able to revive their own “dead” battery pack by installing this unofficial firmware, so whether intentional or not, it seems there’s little debate that usable batteries are indeed being prematurely marked as defective.

Proper cell balancing is key even in DIY projects, so we do have to agree that it seems more than a little unusual that Dyson would intentionally turn off this important feature in their packs. But the jury is still out on whether or not Sir James is trying to pull a fast one on his customers — as Hanlon’s Razor states, “never attribute to malice that which is adequately explained by stupidity”.

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When Battery Rebuilds Go Wrong: Understanding BMSs, Spot Welders, And Safety

Batteries are amazing. Batteries are horrible. Batteries are a necessary evil in today’s world of portable everything. If you’re reading this sentence, even if it’s not on a mobile device, somewhere there is a battery involved. They’re that ubiquitous. There’s another thing batteries are: Expensive! And at $350 each for a specialized battery, [Linus] of Linus Tech Tips decided to take battery repair into his own hands.

Rather than do a quick how-to video about putting new cells in an old enclosure, [Linus] does a deep dive into the equipment, skills, and safety measures needed when dealing with Lithium Ion cells. And if you watch the video through, you’ll even get to see those safety measures put to good use!

The real meat of the video comes toward the end however, with its explanation of the different Battery Management Systems (BMS), and a discussion of the difficulty of doing battery repair correctly and safely. Lastly, the video covers something a bit more sinister: Batteries that are made to resist being repaired with new cells; DRM for batteries, so to speak.

Overall we found the video informative, and we hope you do too. You might also enjoy this peek into the chemistry behind your favorite battery types.

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A LiPo Cell Makes A 4AA Pack For A GameBoy

Electronic toys of yesteryear were fantastic objects of desire, but came with the fatal flaw of requiring batteries. Batteries that cost more than the average youngster’s pocket money and for which the pestered parent were usually unwilling to fork out every couple of days to support an incessant playing habit. It’s something [Sen] has addressed for the Nintendo Game Boy, and rather than cutting the device up and soldering wires, the result is a unit that neatly slots into the existing 4AA battery enclosure.

The Nintendo rechargable Game Boy pack.
Much more convenient than Nintendo’s own effort!

Electrically it’s a simple case of wiring up an Adafruit module and a pouch cell, but that’s not the essence of the job in this case. Instead a huge quantity of work and iteration has gone into CAD design to the perfect-fitting pack. It’s sure to be a boon for today’s Game Boy player, but much more than that it should be of interest to owners of far more devices that take four AA cells. Most of us probably keep a few packs of AAs for just those moments, perhaps meanwhile something like this could be a handy thing to have instead.

More traditional conversions resort to extreme measures, as with this Game Boy Color.

Review: Battery Spot Welders, Why You Should Buy A Proper Spot Welder

Making battery packs is a common pursuit in our community, involving spot-welding nickel strips to the terminals on individual cells. Many a pack has been made in this way, using reclaimed 18650 cells taken from discarded laptops. Commercial battery spot welders do a good job but have a huge inrush current and aren’t cheap, so it’s not uncommon to see improvised solutions such as rewound transformers taken out of microwave ovens. There’s another possibility though, in the form of cheap modules that promise the same results using a battery pack as a power supply.

With a love of putting the cheaper end of the global electronic marketplace through its paces for the entertainment of Hackaday readers I couldn’t resist, so I parted with £15 (about $20), for a “Mini Spot Welder”, and sat down to wait for the mailman to bring me the usual anonymous grey package.

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How To Run Alternative Batteries On The DJI Mavic Mini

Rechargeable batteries are ubiquitous these days, freeing us from the expense and hassle of using disposable cells. However, this has come with the caveat that many manufacturers demand their equipment only be used with their own official batteries. [aeropic] wasn’t a fan of this, so built a circuit to allow his DJI Mavic Mini to fly with any batteries he pleased.

The Mavic Mini uses I2C to communicate with official packs, making the hack relatively straightforward. [aeropic] built a board nicknamed B0B, which tells the drone what it wants to hear and lets it boot up with unofficial batteries installed. The circuit uses a PIC12F1840 to speak to the drone, including reporting voltage on the cells installed. Notably, it only monitors the whole pack, before dividing the voltage to represent the value of individual cells, but it shouldn’t be a major problem in typical use. Combined with a few 3D printed components to hold everything together, it allows you to build your own cheap pack for the Mavic Mini with little more than a PCB and a few 18650 cells.

It’s always good to see hackers getting out and doing the bread and butter work to get around restrictive factory DRM measures, whether its on music, printer cartridges, or drone batteries. We’ve even seen the scourge appear on litter boxes, too. Video after the break.

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